If you’ve been considering e-cigarettes to wean yourself off tobacco cigarettes, you should probably refrain from doing so. A latest study by Harvard T.H. Chan School of Public Health revealed that about 75% of all flavored cigarettes tested by researchers contain toxic chemicals that contribute to the development of ‘popcorn lung’, a deadly respiratory disease. The culprit, according to the study, is diacetyl, a chemical linked to bronchiolitis obliterans.

Diacetyl is used as a substitute for butter in foods such as cupcakes and cotton candy as it imparts a unique flavor. When consumed via food, diacetyl is regarded as being safe. However, according to the United States National Institute for Occupational Safety and Health, the same chemical, when inhaled over long periods, could prove hazardous to health.

The hazardous nature of diacetyl came to the fore after numerous workers at factories that manufacture microwaveable popcorn were diagnosed with bronchiolitis obliterans, a respiratory disease that could turn fatal. What compounds this fact is that this disease has no known cure, and a patient’s only hope for survival in advanced cases is a lung transplant. Diacetyl causes scarring and inflammation in the lungs, and blocks the airflow by constricting the tiny airways (bronchioles) that run through the lungs.

The researchers who conducted the study said that healthcare agencies need to give urgent attention to the harmful effect of this toxic chemical in e-cigarettes given their soaring popularity worldwide. However, not all scientists and healthcare officials are convinced that e-cigarettes are indeed harmful. In fact, earlier, in 2015, Public Health England reportedly recommended that smokers shift to e-cigarettes because they were safer than conventional e-cigarettes. The World Health Organization, however, has said that e-cigarettes are not as safe as they are widely considered to be.